People read for many different purposes, and they may read the same text very differently depending upon those purposes. Natural reading situations, as well as lab paradigms, vary in terms of their memory and their comprehension demands. Different cognitive operations may be required for immediate comprehension of meaning than for faithful preservation of lexical and structural information required for verbatim retention tasks. We will study the effects of task demands on the word-by-word reading times for text in which linguistic attributes are systematically varied. We will vary (a) the lexical, semantic and syntactic attributes of individual words, and (b) contextual factors including paragraph structure, coherence links, and semantic and syntactic predictability. We will measure reading times, subsequent comprehension and retention accuracy and subjective ratings of text: e.g., importance of individual words, their qualitative role in the sentence, the locations of "natural divisions" and the number and types of meaning and structural units in text. These data will test quantitative theories about the stages of cognitive and linguistic processing during perceptual coding of text. The models account for reading time patterns characteristic of phrase structure coding exhibited when subjects read for faithful retention, and for the lexical-semantic patterns exhibited when Ss read for immediate comprehension. For a given body of text and a fixed performance task, individuals differ from one another in their patterns of word-by-word reading times, and presumably in their underlying reading strategy. We will examine individual RTs, and flexibility in reading strategies (a) for fast vs. slow readers, (b) for good vs. poor readers (based on accuracy), (c) for variations in practice, (d) for two age groups (5th grade & college). The qualitative nature and the range of individual differences should have implications for reading instruction, remedial education, dyslexia, computer aided instruction and human factors in the work and home environment. The methodology has promise for use in clinical research and applications with cognitively impaired geriatric populations (including Alzheimer's and other dementias).